Asymmetric pyrene derivative and organic electroluminescence device employing the same

ABSTRACT

Asymmetric pyrene derivatives having specific structure. An organic EL device comprising at least one organic thin film layer including a light emitting layer sandwiched between a pair of electrode consisting of an anode and a cathode, wherein the organic thin film layer comprises at least one kind selected from the aforementioned asymmetric pyrene derivatives singly or as a component of mixture thereof. An organic EL device exhibiting a great efficiency of light emission and having a long lifetime, and also asymmetric pyrene derivatives for realizing the organic EL device are provided.

TECHNICAL FIELD

The present invention relates to an asymmetric pyrene derivative and anorganic electroluminescence (“electroluminescence” will be occasionallyreferred to as “EL”, hereinafter) device employing the same, moreparticularly, to an organic EL device exhibiting a great efficiency oflight emission and having a long lifetime, and also to the asymmetricpyrene derivative for realizing the organic EL device.

BACKGROUND ART

An organic electroluminescence device is a spontaneous light emittingdevice which utilizes the principle that a fluorescent substance emitslight by energy of recombination of holes injected from an anode andelectrons injected from a cathode when an electric field is applied.Since an organic EL device of the laminate type driven under a lowelectric voltage was reported by C. W. Tang et al. of Eastman KodakCompany (C. W. Tang and S. A Vanslyke, Applied Physics Letters, Volume51, Pages 913, 1987), many studies have been conducted on organic ELdevices using organic materials as the constituting materials. Tang etal. used a laminate structure using tris(8-hydroxyquinolinol aluminum)for the light emitting layer and a triphenyldiamine derivative for thehole transporting layer. Advantages of the laminate structure are thatthe efficiency of hole injection into the light emitting layer can beincreased, that the efficiency of forming excited particles which areformed by blocking and recombining electrons injected from the cathodecan be increased, and that excited particles formed among the lightemitting layer can be enclosed. As the structure of the organic ELdevice, a two-layered structure having a hole transporting (injecting)layer and an electron transporting and light emitting layer and athree-layered structure having a hole transporting (injecting) layer, alight emitting layer and an electron transporting (injecting) layer arewell known. To increase the efficiency of recombination of injectedholes and electrons in the devices of the laminate type, the structureof the device and the process for forming the device have been studied.

As the light emitting material of the organic EL device, chelatecomplexes such as tris(8-quinolinolato)aluminum, coumarine derivatives,tetraphenylbutadiene derivatives, bisstyrylarylene derivatives andoxadiazole derivatives are known. It is reported that light in thevisible region ranging from blue light to red light can be obtained byusing these light emitting materials, and development of a deviceexhibiting color images is expected (refer to, for example, Patentliterature 1, Patent literature 2, and Patent literature 3).

Further, a device using asymmetrical pyrene derivative as the lightemitting material is disclosed in Patent literatures 4 to 7, and adevice using an asymmetrical anthracene derivative as the light emittingmaterial is disclosed in Patent literature 8. Although these derivativesare used as the material for emitting blue light, further improvementsof the lifetime thereof have been desired. In addition, development of aderivative being not easily affected by oxidization has been desiredbecause of low oxidative stability of existing derivatives.

Patent literature 1: Japanese Patent Application

-   -   Laid-Open No. Heisei 8(1996)-239655

Patent literature 2: Japanese Patent Application

-   -   Laid-Open No. Heisei 7(1995)-138561

Patent literature 3: Japanese Patent Application

-   -   Laid-Open No. Heisei 3(1991)-200289

Patent literature 4: Japanese Patent Application

-   -   Laid-Open No. 2001-118682

Patent literature 5: Japanese Patent Application

-   -   Laid-Open No. 2002-63988

Patent literature 6: Japanese Patent Application

-   -   Laid-Open No. 2004-75567

Patent literature 7: Japanese Patent Application

-   -   Laid-Open No. 2004-83481

Patent literature 8: International PCT publication No. WO 04/018587

DISCLOSURE OF THE INVENTION

The present invention has been made to overcome the above problems andhas an objective of providing an organic electroluminescence deviceexhibiting a great efficiency of light emission and having a longlifetime, and also to an asymmetric pyrene derivative for realizing theorganic EL device.

As a result of intensive researches and studies to achieve the aboveobjective by the present inventors, it was found that employing anasymmetric derivative represented by any of following general formulaefrom (1) to (3) as a constituting material for an organic thin film ofan organic EL device enables to provide the organic EL device exhibitinga great efficiency of light emission and having a long lifetime.

Therefore, the present invention provides an asymmetric pyrenederivative represented by any of the following general formulae (1) to(3):

In the general formula (1), Ar and Ar′ each represents a substituted orunsubstituted aromatic group having 6 to 50 ring carbon atoms;

L and L′ each represents a substituted or unsubstituted phenylene group,a substituted or unsubstituted naphthalenylene group a substituted orunsubstituted fluorenylene group or a substituted or unsubstituteddibenzosilolylene group;

m represents an integer of 0 to 2, n represents an integer of 1 to 4, 8represents an integer of 0 to 2 and t represents an integer of 0 to 4;and,

L or Ar bonds to any one of 1 to 6 position of pyrene, also L′ or Ar′bonds to any one of 6 to 10 position thereof,

however, when n+t is an even number, Ar, Ar′, L and L′ satisfy afollowing requirement (1) or a requirement (2):

In the general formula (3), Ar, Ar′, L, L′, m and 8 are the same withaforementioned.

Moreover, the present invention provides an organic EL device comprisingat least one organic thin film layer including a light emitting layersandwiched between a pair of electrode consisting of an anode and acathode, wherein the organic thin film layer comprises at least one kindselected from the aforementioned asymmetric pyrene derivatives singly oras a component of mixture thereof.

An organic EL device containing an asymmetric pyrene derivative of thepresent invention exhibits a great efficiency of light emission and hasa long lifetime.

THE PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION

The present invention provides an asymmetric pyrene derivativerepresented by a following general formula (1):

(1) Ar≠Ar′ and/or L≠L′ (wherein ≠ means that each group has a differentstructure)

(2) when Ar=Ar′ and L=L′

(2-1) m≠s and/or n≠t, or

(2-2) when m=s and n=t,

(2-2-1) both L and L′ or pyrene bond respectively to a differentposition of Ar and Ar′ or (2-2-2) both L and L′ or pyrene bondrespectively to the same position of Ar and Ar′ excluding a case whereboth L and L′ or both Ar and Ar′ bond respectively to 1 and 6, or 2 and7 positions thereof.

In the general formula (2), Ar, Ar′, L, L′, m, s and t are the same withthe aforementioned.

L′ or Ar′ bonds to any one of 2 to 10 positions of the pyrene, however,when t is an odd number, Ar, Ar′, L and L′ satisfy a followingrequirement (1′) or a requirement (2′):

(1′) Ar≠Ar′ and/or L≠L′ (wherein ≠ means that each group has a differentstructure)

(2′) when Ar=Ar′ and L=L′

(2-1′) m≠and/or t≠1, or

(2-2′) when m=s and t=1,

(2-2-1′) both L and L′ or pyrene each bonds respectively to differentpositions of Ar and Ar′, or

(2-2-2′) both L and L′ or pyrene each bonds to the same positions of Arand Ar′ excluding a case where L′ or Ar′ bonds to 6 position thereof.

In the general formula (1), Ar and Ar′ each represents a substituted orunsubstituted aromatic group having 6 to 50 ring carbon atoms.

Examples of the substituted or unsubstituted aromatic group includephenyl group, 1-naphthyl group, 2-naphthyl group, 1-anthryl group,2-anthryl group, 9-anthryl group, 9-(10-phenyl)anthryl group,9-(10-naphtyl-1-yl)anthryl group, 9-(10-naphtyl-2-yl)anthryl group,1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group,4-phenanthryl group, 9-phenanthryl group, 1-naphthacenyl group,2-naphthacenyl group, 9-naphthacenyl group, 1-pyrenyl group, 2-pyrenylgroup, 4-pyrenyl group, 2-biphenylyl group, 3-biphenylyl group,4-biphenylyl group, p-terphenyl-4-yl group, p-terphenyl-3-yl group,p-terphenyl-2-yl group, m-terphenyl-4-yl group, m-terphenyl-3-yl group,m-terphenyl-2-yl group, o-tolyl group, m-tolyl group, p-tolyl group,p-t-butylphenyl group, 3-methyl-2-naphthyl group, 4-methyl-1-naphthylgroup, 4-methyl-1-anthryl group and the like.

Among the aforementioned, preferred examples includes phenyl group,1-naphthyl group, 2-naphthyl group, 9-(10-phenyl)anthryl group,9-(10-naphtyl-1-yl)anthryl group, 9-(10-naphtyl-2-yl)anthryl group,9-phenanthryl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group,2-biphenylyl group, 3-biphenylyl group, 4-biphenylyl group, o-tolylgroup, m-tolyl group, p-tolyl group, p-t-butylphenyl group and the like.

Further, the aforementioned aromatic groups may be substituted by asubstituent such as alkyl group (methyl group, ethyl group, propylgroup, isopropyl group, n-butyl group, s-butyl group, isobutyl group,t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octylgroup, hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group,2-hydroxyisobutyl group, 1,2-dihydroxyethyl group,1,3-dihydroxy-isopropyl group, 2,3-dihydroxy-t-butyl group,1,2,3-trihydroxypropyl group, chloromethyl group, 1-chloroethyl group,2-chloroethyl group, 2-chloroisobutyl group, 1,2-dichloroethyl group,1,3-dichloroisopropyl group, 2,3-dichloro-t-butyl group,1,2,3-trichloropropyl group, bromomethyl group, 1-bromoethyl group,2-bromoethyl group, 2-bromoisobutyl group, 1,2-dibromoethyl group,1,3-dibromoisopropyl group, 2,3-dibromo-t-butyl group,1,2,3-tribromopropyl group, iodomethyl group, 1-iodoethyl group,2-iodoethyl group, 2-iodoisobutyl group, 1,2-diiodoethyl group,1,3-diiodoisopropyl group, 2,3-diiodo-t-butyl group, 1,2,3-triiodopropylgroup, aminomethyl group, 1-aminoethyl group, 2-aminoethyl group,2-aminoisobutyl group, 1,2-diaminoethyl group, 1,3-diaminoisopropylgroup, 2,3-diamino-t-butyl group, 1,2,3-triamino-propyl group,cyanomethyl group, 1-cyanoethyl group, 2-cyanoethyl group,2-cyanoisobutyl group, 1,2-dicyanoethyl group, 1,3-dicyanoisopropylgroup, 2,3-dicyano-t-butyl group, 1,2,3-tricyano-propyl group,nitromethyl group, 1-nitroethyl group, 2-nitroethyl group,2-nitroisobutyl group, 1,2-dinitroethyl group, 1,3-dinitroisopropylgroup, 2,3-dinitro-t-butyl group, 1,2,3-trinitropropyl group,cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexylgroup, 4-methylcyclohexyl group, 1-adamanthyl group, 2-adamanthyl group,1-norbornyl group, 2-norbornyl group), alkoxy group having 1 to 6 carbonatoms (ethoxy group, methoxy group, i-propoxy group, n-propoxy group,s-butoxy group, t-butoxy group, pentoxy group, hexyloxy group,cyclopentoxy group, cyclohexyloxy group and etc.), aryl group having 5to 40 ring carbon atoms, amino group substituted by aryl group having 6to 40 ring carbon atoms, ester group containing aryl group having 5 to40 ring carbon atoms, ester group containing alkyl group having 1 to 6carbon atoms, cyano group, nitro group, halogen atom and the like.

In the general formula (1), L and L′ each represents a substituted orunsubstituted phenylene group, a substituted or unsubstitutednaphtharenylene, a substituted or unsubstituted fluorenylene group or asubstituted or unsubstituted a dibenzosilolylene group, and asubstituted or unsubstituted phenylene group or a substituted orunsubstituted fluorenylene group is preferred.

In addition, the substituent thereof includes the same with theaforementioned aromatic groups.

In the general formula (1), m represents an integer of 0 to 2(preferably 0 to 1), n represents an integer of 1 to 4 (preferably 1 to2), s represents an integer of 0 to 2 (preferably 0 to 1) and trepresents an integer of 0 to 4 (preferably 0 to 2), and, in the generalformula (1), L or Ar bonds to any one of 1 to 5 positions of the pyrene,and also L′ or Ar′ bonds to any one of 6 to 10 positions thereof,however, when n+t is an even number, Ar, Ar′, L and L′ satisfy afollowing requirement (1) or a requirement (2):

(1) Ar≠Ar′ and/or L=L′, wherein ≠ means that each group has a differentstructure,

(2) when Ar=Ar′ and L=L′,

(2-1) m≠s and/or n≠t, or

(2-2) when m=sand n=t,

(2-2-1) both L and L′ or pyrene bond respectively to a differentposition of Ar and Ar′ or (2-2-2) both L and L′ or pyrene bondrespectively to the same position of Ar and Ar′ excluding a case whereboth L and L′ or both Ar and Ar′ bond respectively to 1 and 6, or 2 and7 positions thereof.

Further, the asymmetric pyrene derivatives of the present inventioninclude the compounds represented by a following general formula (2):

In the general formula (2), Ar, Ar′, L, L′, m, s and t are the same withthe aforementioned. Further, preferable examples thereof and examples ofthe substituent thereof are the same with aforementioned. In addition,L′ or Ar′ bonds to any one of 2 to 10 positions of pyrene, however, inthe general formula (2), when t is an odd number, Ar, Ar′, L and L′satisfy a following requirement (1′) or a requirement (2′);

(1) Ar≠Ar′ and/or L=L′, wherein ≠ means that each group has a differentstructure,

(2) when Ar=Ar′ and L=L′,

(2-1′) m≠s and/or t≠1, or

(2-2′) when m=s and t=1,

(2-2-1′) both L and L′ or pyrene each bonds respectively to differentpositions of Ar and Ar′, or

(2-2-2′) both L and L′ or pyrene each bonds to the sane positions of Arand Ar′ excluding a case where L′ or Ar′ bonds to 6 position thereof.

In addition, the asymmetric pyrene derivative of the present inventionis preferably the compounds represented by a following general formula(3).

In the general formula (3), Ar, Ar′, L, L′, m and s are the same withthe aforementioned, and preferable examples thereof and examples of thesubstituent thereof are the same with aforementioned.

Specific examples of the asymmetric pyrene derivatives represented bythe general formulae (1) to (3) of the present invention include thefollowing compounds, though not limited thereto.

A preparation method of the asymmetric pyrene derivatives of the presentinvention is explained as follows:

The asymmetric pyrene derivatives represented by the general formula (1)to (3) of the present invention and precursors thereof may be obtainedby using a pyrene halide compound and an aryl-boronic acid compound, oran aryl-halide compound and pyrenyl-boronic acid compound as a startingmaterial and applying methods such as Suzuki-coupling reaction and thelike. In addition, a combination of a halogenation reaction, anesterification by boric acid and Suzuki-coupling reaction is applied tothe precursor as appropriated, and then, the asymmetric pyrenederivatives represented by the general formula (1) to (3) are obtained.

So far, many reports on Suzuki-coupling reaction have been published(Chem. Rev. Vol. 954, No. 7, 2457 (1995), etc.), therefore, it may becarried out in the reaction conditions described therein. The reactionis carried out generally at normal pressure in inert gas atmosphere suchas nitrogen, argon, helium and the like, and also under pressurizedcondition as appropriated. The reaction temperature is in the range offrom 15 to 300° C. preferably from 30 to 200° C.

The reaction solvent includes water, aromatic hydrocarbons such asbenzene, toluene and xylene, ether such as 1,2-dimethoxyethane,diethyl-ether, methyl-t-butylether, tetrahydrofuran, and dioxane,saturated hydrocarbon such as pentane, hexane, heptane, octane andcyclohexane, halogenated hydrocarbon such as dichloromethane,chloroform, carbon tetrachloride, 1,2-dichloroethane and1,1,1-trichloroethane, nitrile such as acetonitrile and benzonitrile,ester such as ethylacetate, methylacetate and butylacetate, amide suchas N,N-dimethylformamide, N,N-dimethylacetoamide andN-methylpyrrolidone, and the solvent may be used singly or incombination of two or more kind thereof. Among them, toluene;1,2-dimethoxyethan, dioxane and water are preferred. An amount of thesolvent is from 3 to 50 fold by weight, preferably 4 to 20 fold byweight to an aryl-boronic acid and a derivative thereof (or apyrenyl-boronic acid and a derivative thereon.

A base to be used for the reaction includes, for example, sodiumcarbonate, potassium carbonate, sodium hydroxide, potassium hydroxide,sodium bicarbonate, potassium bicarbonate, magnesium carbonate, lithiumcarbonate, potassium fluoride, cesium fluoride, cesium chloride, cesiumbromide, cesium carbonate, potassium phosphate, sodium methoxide,potassium t-butoxide, sodium t-butoxide and lithium t-butoxide, andsodium carbonate is preferred. An amount of the base to be used isgenerally from 0.7 to 10 mole in equivalence, preferably from 0.9 to 6mole in equivalence to an aryl-boronic acid and a derivatives thereof(or a pyrenyl-boronic acid and a derivative thereof).

Catalysts to be used for the reaction include, for example, a palladiumcatalyst such as tetrakis(triphenylphosphine)palladium,dichlorobis(triphenylphosphine)palladium,dichloro[bis(diphenylphosphine)ethane]palladium,dichloro[bis(diphenylphosphine)propane]palladium,dichloro[bis(diphenylphosphine)butane]palladium,dichloro[bis(diphenylphosphine)ferrocene]palladium, and a nickelcatalyst such as tetrakis(triphenylphosphine) nickeldichlorobis(triphenylphosphine)nickeldichloro[bis(diphenylphosphine)ethane]nickeldichloro[bis(diphenylphosphine)propane]nickel,dichloro[bis(diphenylphosphine)butane]nickel,dichloro[bis(diphenylphosphine)ferrocene]nickel. Thetetrakis(triphenylphosphine)palladium is preferred. An amount of thecatalysts to be used is generally from 0.001 to 1 mole in equivalence,preferably from 0.01 to 0.1 mole in equivalence to an anthracenederivative halide.

Halogen of pyrene halide compounds and aryl halide compounds includesiodine atom, bromine atom, chlorine atom and so forth, and iodine atomand bromine atom are preferred.

Although a halogenation reagent for halogenation is not limited, forexample, N-succinic acid imide halide is in particular preferably to beused. An amount of the halogenation reagent to be used is generally from0.8 to 10 mole in equivalence, preferably from 1 to 5 mole inequivalence to a base material.

The reaction is carried out generally in an inert solvent under inertatmosphere such as nitrogen, argon, helium. The inert solvents to beused include N,N-dimethylformamide, N,N-dimethylacetamide,N-methylpyrrolidone, dimethyl sulfoxide, carbon tetrachloride,chlorobenzene, dichlorobenzene, nitrobenzene, toluene, xylene methylcellosolve, ethyl cellosolve, water and the like, andN,N-dimethylformamide and N-methylpyrrolidone are preferred. An amountof the solvent to be used is generally from 3 to 50 fold by weight,preferably from 5 to 20 fold by weight to a base material. The reactiontemperature is generally from 0 to 200° C., preferably from 20 to 120°C.

The esterification by boric acid may be carried out in accordance withknown methods (Japan Chemical Society' editorial, The ExperimentalChemistry Course No. 4 edition, Vol 24, 61-90; J. Org. Chem., Vol. 60,7508, etc.). For example, by way of lithiation or Grignard reaction ofan arylhalide compound (or a pyrenylhalide compound), the esterificationby boric acid is carried out generally under inert atmosphere such asnitrogen, argon, helium and by using an inert solvent as a reactionsolvent. The solvents include, for example, saturated hydrocarbon suchas pentane, hexane, heptane, octane and cyclohexane, ether such as1,2-dimethoxyethane, diethylether, methyl-t-butylether, tetrahydrofuranand dioxane, aromatic hydrocarbon such as benzene, toluene and xylene.These may be used singly or as mixture thereof and dimethylether andtoluene are preferred. An amount of the solvent to be used is generallyfrom 3 to 50 fold by weight, preferably from 4 to 20 fold by weight toan arylhalide compound.

The lithiation reagent to be used includes, for example, alkyl metalreagent such as n-butyllithium, t-butyllithium, phenyllthium andmethyllithium, amido-base such as lithium di-isopropylamide andlithiumbistrimethylsilylamide, and n-butyllithium is preferred. Further,Grignard reagent may be prepared by reacting an arylhalide compound (ora pyrenylhalide compound) and a magnesium metal Trialkyl borate to beused includes trimethyl borate, triethyl borate, tri-isopropyl borate,tri-isobutyl borate and the like, and trimethyl borate and tri-isopropylborate are preferred.

Each amount of the lithiation reagent and the magnesium metal to be usedis generally from 1 to 10 mole in equivalence, preferably from 1 to 2mole in equivalence respectively to an arylhalide compound (or apyrenylhalide compound). An amount of trialkyl borate to be used isgenerally from 1 to 10 mole in equivalence, preferably from 1 to 5 molein in equivalence to an arylhalide compound (or a pyrenylhalidecompound). The reaction temperature is from −100 to 50° C., inparticular preferably from −75 to 10° C.

The asymmetric pyrene derivatives of the present invention are preferredfor a light emitting material of the organic EL device, and particularlypreferred for a host material of the organic EL device.

An organic EL device of the present invention comprises at least oneorganic thin film layer including a light emitting layer sandwichedbetween a pair of electrode consisting of an anode and a cathode,wherein the organic thin film layer comprises at least one kind selectedfrom the asymmetric pyrene derivatives represented by the aforementionedgeneral formulae (1) to (3) singly or as a component of mixture thereof.

In addition, the organic EL device of the present invention is preferredwhen the aforementioned light emitting layer comprises further anarylamine compound and/or a styrylamine compound.

The preferred styrylamine compounds are shown by the following generalformula (4):

In the general formula (4), Ar² represents a group selected from among aphenyl group, a biphenyl group, a terphenyl group, a stilbene group anda distyryl aryl group; Ar³ and Ar⁴ each independently represents ahydrogen atom or an aromatic group having 6 to 20 carbon atoms; furtherAr², Ar³ and Ar⁴ each may be substituted; p represents an integer of 1to 4; and more preferably, at least one of Ar⁸ and Ar⁴ is substitutedwith a styryl group.

In the preceding description, the aromatic group having 6 to 20 carbonatoms includes a phenyl group, a naphthyl group, an anthranyl group, aphenanthryl group, a terphenyl group or the like.

The preferred arylamine compounds are represented by the general formula(5):

In the general formula (5), Ar⁵ to Ar⁷ each independently represents anaryl group having 5 to 40 ring carbon atoms that may be substituted, andq represents an integer of 1 to 4.

In the preceding description, the aryl group having 5 to 40 ring carbonatoms includes a phenyl group, a naphthyl group, chrysenyl group, anaphthacenyl group, an anthranil group, a phenanthryl group, a pyrenylgroup, a coronyl group, a biphenyl group, a terphenyl group, a pyrrolylgroup, a furanyl group, a thiophenyl group, a benz thiophenyl group, anoxadiazolyl group, a diphenyl anthranil group, an indolyl group, acarbazolyl group, a pyridyl group, a benz quinolyl group, afluoranthenyl group, an acenaphthofluoranthenyl group, a stilbene groupor so. Additionally, the aryl group having 6 to 40 carbon atoms may befurther substituted with a substituent, and preferable examples of thesubstituent include an alkyl group having 1 to 6 carbon atoms (an ethylgroup, a methyl group, an i-propyl group, a n-propyl group, a s-butylgroup, a t-butyl group, a pentyl group, a hexyl group, a cyclopentylgroup, a cyclohexyl group, etc.), an alkoxy group having 1 to 6 carbonatoms (an ethoxy group, a methoxy group, an i-propoxy group, a n-propoxygroup, a s-butoxy group, a t-butoxy group, a pentoxy group, a hexyloxygroup, a cyclo pentoxy group, a cyclohexyl oxy group, etc.), an arylgroup having 5 to 40 ring atoms, an amino group substituted with an arylgroup having 5 to 40 ring atoms, an ester group which has an aryl grouphaving 5 to 40 ring atoms, an ester group which has an alkyl grouphaving 1 to 6 carbon atoms, a cyano group, a nitro group, a halogen atomand the like.

The following is a description or the construction of the organic ELdevice of the present invention. Typical examples of the construction ofthe organic EL device of the present invention include:

(1) an anode/a light emitting layer/a cathode;

(2) an anode/a hole injecting layer/a light emitting layer/a cathode;

(3) an anode/a light emitting layer/an electron injecting layer/acathode;

(4) an anode/a hole injecting layer/a light emitting layer/an electroninjecting layer/a cathode;

(5) an anode/an organic semiconductor layer/a light emitting layer/acathode;

(6) an anode/an organic semiconductor layer/an electron barrier layer/alight emitting layer/a cathode;

(7) an anode/an organic semiconductor layer/a light emitting layer/anadhesion improving layer/a cathode;

(8) an anode/a hole injecting layer/a hole transporting layer/a lightemitting layer/an electron injecting layer/a cathode;

(9) an anode/an insulating layer/a light emitting layer/an insulatinglayer/a cathode;

(10) an anode/an inorganic semiconductor layer/an insulating layer/alight emitting layer/an insulating layer/a cathode;

(11) an anode/an organic semiconductor layer/an insulating layer/a lightemitting layer/an insulating layer/a cathode;

(12) an anode/an insulating layer/a hole injecting layer/a holetransporting layer/a light emitting layer/an insulating layer/a cathode;and

(13) an anode/an insulating layer/a hole injecting layer/a holetransporting layer/a light emitting layer/an electron injecting layer/acathode.

Among those, the construction (8) is generally employed in particular;however, the construction of the organic EL device is not limited tothose shown above as the examples.

In addition, although the asymmetric pyrene derivatives of the presentinvention may be employed for any of the above organic layers, it ispreferable that it is contained in a light emitting zone or a holetransporting zone among those construction elements, and an amount to becontained therein may be selected from in the range of from 30 to 100mole %.

In general, the organic EL device is produced on a substrate whichtransmits light. It is preferable that the substrate which transmitslight has a transmittance of light of 50% or greater in the visibleregion of 400 to 700 nm. It is also preferable that a flat and smoothsubstrate is employed. As the substrate which transmits light, forexample, glass sheet and synthetic resin sheet are advantageouslyemployed.

Specific examples of the glass sheet include soda ash glass, glasscontaining barium and strontium, lead glass, aluminosilicate glass,borosilicate glass, barium borosilicate glass and quartz. In addition,specific examples of the synthetic resin sheet include sheet made ofpolycarbonate resins, acrylic resins, polyethylene terephthalate resins,polyether sulfide resins and polysulfone resins.

The anode in the organic EL device of the present invention covers arole of injecting holes into a hole transport layer or into a lightemitting layer, and it is effective that the anode has a work functionof 4.5 eV or greater. Specific examples of the material for the anodeinclude indium tin oxide alloy (ITO), tin oxide (NESA), gold, silver,platinum, copper, etc. With regard to the cathode, its materialpreferably has a small work function with the aim of injecting electronsinto an electron transport layer or into a light emitting layer. Theanode can be prepared by forming a thin film of the electrode materialdescribed above in accordance with a process such as a vapor depositionprocess or a sputtering process.

When the light emitted from the light emitting layer is observed throughthe anode, it is preferable that the anode has a transmittance of theemitted light greater than 10%. It is also preferable that the sheetresistivity of the anode is several hundred Ω/□ or smaller. Thethickness of the anode is, in general, selected in the range of from 10nm to 1 μm and preferably in the range of from 10 to 200 nm.

In the organic EL device of the present invention, the light emittinglayer has the following functions:

(1) The injecting function: the function of injecting holes from theanode or the hole injecting layer and injecting electrons from thecathode or the electron injecting layer when an electric field isapplied;

(2) The transporting function: the function of transporting injectedcharges (electrons and holes) by the force of the electric field; and

(3) The light emitting function: the function of providing the field forrecombination of electrons and holes and leading the recombination tothe emission of light.

As the process for forming the light emitting layer, a well knownprocess such as the vapor deposition process, the spin coating processand the LB process can be employed. It is preferable that a lightemitting layer is a molecular sedimentation film particularly. Here, themolecular sedimentation film is defined as a thin film formed bysedimentation of a gas phase material compound or a thin film formed bycondensation of a liquid phase material compound. The molecularsedimentation film may be differentiated from a thin film (a molecularbuild-up film) formed by the LB process, based on the differencesbetween agglomeration structures and higher-order structures, and alsothe differences resulting from functionalities thereof.

In addition, as shown in Japanese Patent Application Laid-open No.Showa57(1982)-51781, to form a light emitting layer, a thin film may beformed in accordance with the spin coating and the like of the solutionto be prepared by dissolving a binder such as resin and a materialcompound in solvent.

In the present invention, any well known light emitting material otherthan a light emitting material consisting of an asymmetric pyrenederivative of the present invention may be optionally contained in thelight emitting layer; or a light emitting layer containing other wellknown light emitting layer may be laminated with the light emittinglayer comprising the light emitting material of the present inventioneach in an extent of not obstructing to achieve the objective of thepresent invention respectively.

In the present invention, the hole injecting layer and the holetransporting layer are layers which assist injection of holes into thelight emitting layer and transport the holes to the light emitting zone.The layers exhibit a great mobility of holes and, in general have anionization energy as small as 5.5 eV or smaller. For the hole injectinglayer and the hole transporting layer, a material which transports holesto the light emitting layer at a small strength of the electric field ispreferable. A material which exhibits, for example, a mobility of holesof at least 10⁻⁴ cm²/V·sec under application of an electric field offrom 10⁴ to 10⁶ V/cm is preferable. As for such material, any arbitrarymaterial selected from conventional material commonly used as a chargetransporting material for the holes in photoconduction materials andwell known material employed for the hole injecting layer in the ELdevice is usable.

Further examples include triazole derivatives (refer to U.S. Pat. No.3,112,197, etc.), oxadiazole derivatives (refer to U.S. Pat. No.3,189,447, etc.), imidazole derivatives (refer to Japanese ExaminedPatent KOKOKU No. Shou 37-16096, etc.), polyarylalkane derivatives referto U.S. Pat. Nos. 3,615,402, 3,820,989 and 3,542,544, Japanese ExaminedPatent KOKOKU Nos. Shou 45-555 and Shou 51-10983, Japanese UnexaminedPatent Application Laid-Open Nos. Shou 51-93224, Shou 55-17105, Shou56-4148, Shou 55-108667, Shou 55-156953, Shou 56-36656, etc.),pyrazoline derivatives and pyrazolone derivatives (refer to U.S. Pat.Nos. 3,180,729 and 4,278,746, Japanese Unexamined Application PatentLaid-Open Nos. Shou 55-88064, Shou 55-88065, Shou 49-105537, Shou65-51086, Shou 56-80051, Shou 56-88141, Shou 57-45545, Shou 54-112637,Shou 55-74546, etc.), phenylenediamine derivatives (refer to U.S. Pat.No. 3,615,404, Japanese Examined Patent KOKOKU Nos. Shou 51-10105, Shou46-3712 and Shou 47-25336, Japanese Unexamined Patent ApplicationLaid-Open Nos. Shou 54-53435, Shou 54-110536, Shou 54-119925, etc.),arylamine derivatives (refer to U.S. Pat. Nos. 3,567,450, 3,180,703,3,240,597, 3,658,520, 4,232,103, 4,175,961 and 4,012,376, JapaneseExamined Patent KOKOKU Nos. Shou 49-36702 and Shou 39-27577, JapaneseUnexamined Patent Application Laid-Open Nos. Shou 56-144250, Shou56-119132 and Shou 56-22437, West German Patent No. 1,110,518, etc.),chalcone derivatives which is substituted with amino group (refer toU.S. Pat. No. 3,526,501, etc.), oxazole derivatives (disclosed in U.S.Pat. No. 3,257,203, etc.), styryl anthracene derivatives (refer toJapanese Unexamined Patent Application Laid-Open No. Shou 56-46234,etc.), fluorenone derivatives (refer to Japanese Unexamined PatentApplication Laid-Open No. Shou 54-110837, etc.), hydrazone derivatives(refer to U.S. Pat. No. 3,717,462, Japanese Unexamined PatentApplication Laid-Open Nos. Shou 54-59143, Shou 55-52063, Shou 55-52064,Shou 55-46760, Shou 55-85495, Shou 57-11350, Shou 57-148749, Hei2-311591, etc.), stilbene derivatives (refer to Japanese UnexaminedPatent Application Laid-Open Nos. Shou 61-210363, Shou 61-228451, Shou61-14642, Shou 61-72255, Shou 62-47646, Shou 62-36674, Shou 62-10652,Shou 62-30255, Shou 60-93455, Shou 60-94462, Shou 60-174749, Shou60-175052, etc.), silazane derivatives (U.S. Pat. No. 4,950,950),polysilane-based copolymers (Japanese Unexamined Patent ApplicationLaid-Open No. Hei 2-204996), aniline-based copolymers (JapaneseUnexamined Patent Application Laid-Open No. Hei 2-282263), anelectroconductive polymer oligomer which is disclosed in JapaneseUnexamined Patent Application Laid-Open No Hei 1-211399 (particularly,thiophene oligomer), etc.

With regard to the material of the hole injecting layer, the abovematerials are also employable, however, porphyrin compounds, aromatictertiary amine compounds and styryl amine compounds (refer to U.S. Pat.No. 4,127,412, Japanese Unexamined Patent Application Laid-Open Nos.Shou 53-27033, Shou 54-58445, Shou 54-149634, Shou 54-64299, Shou55-79450, Shou 55-144250, Shou 56-119132, Shou 61-295558, Shou 61-98353,Shou 63-295695, etc.) are preferable and the aromatic tertiary aminecompounds are particularly preferable.

Further examples include, for example,4,4′-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (abbreviated as NPDhereunder) having 2 fused aromatic rings in its molecular described inU.S. Pat. Nos. 5,061,569, 4,4′,4″-tris(N-(3-methylphenyl)-N-phenylamino) triphenyl amine (abbreviated as MDATAhereunder) made by connecting three triphenyl amine units to form a starburst type, etc.

Further, in addition to the aforementioned asymmetric pyrene derivativesas a material for the light emitting layer, inorganic compound such asp-type silicon, p-type silicon carbide or so is employable as thematerial for the hole injecting layer.

To form the hole injecting layer or the hole transporting layer, a thinfilm may be formed from the material for the hole injecting layer or thehole transporting layer, respectively, in accordance with a well knownprocess such as the vacuum vapor deposition process, the spin coatingprocess, the casting process and the LB process. Although the thicknessof the hole injecting layer and the hole transporting layer is notparticularly limited, the thickness is usually from 5 nm to 5 μm.

In the organic EL device of the present invention, the organicsemiconductor layer assists to inject the holes or to inject theelectrons into the light emitting layer, and it is preferable for theorganic semiconductor layer to have a electric conductivity of 10⁻¹⁰S/cm or greater. With regard to a material for the organic semiconductorlayer, electroconductive oligomers such as an oligomer having thiophene,an oligomer having arylamine disclosed in Japanese Patent ApplicationLaid-Open No. Heisei 8(1996)-193191 and so on, electroconductivedendrimers such as a dendrimer having an arylamine and so on areemployable.

The electron injection layer in the organic EL device of the presentinvention is a layer which assists injection of electrons into the lightemitting layer and exhibits a great mobility of electrons. Among theelectron injecting layers, an adhesion improving layer is a layer madeof a material exhibiting excellent adhesion with the cathode.

Further, it has been known that interference between luminescencedirectly coming from an anode and luminescence coming through reflectionby an electrode is caused since a light emitted in an organic EL deviceis reflected by an electrode (in this case, a cathode). In order toutilize the interference effect efficiently, a thickness of an electrontransferring layer is selected from the range of several nm to severalμm accordingly. It is preferable that an electron mobility is at least10⁻⁵ cm²/Vs or more when an electric field of from 10⁴ to 10⁶V/cm isapplied.

As the material for the electron injecting layer, 8-hydroxyquinoline,metal complexes of derivatives thereof and oxadiazole derivatives arepreferable. Examples of the 8-hydroxyquinoline and metal complexes ofderivatives thereof include metal chelates of oxinoid compoundsincluding chelates of oxine (in general 8-quinolinol or8-hydroxyquinoline). For example, tris(8-quinolinol)aluminum (Alq) canbe employed as the electron injecting material.

Further, examples of the oxadiazole deliveries include an electrontransfer compound shown as the following general formulae:

wherein Ar¹, Ar², Ar³, Ar⁵, Ar⁸ and Ar⁹ each independently represents asubstituted or unsubstituted aryl group, which may be the same with ordifferent from each other; Ar⁴, Ar⁷ and Ar⁸ each independentlyrepresents a substituted or unsubstituted arylene group, which may bethe same with or different from each other.

Examples of the aryl group include a phenyl group, a biphenyl group, ananthranil group, a perilenyl group and a pyrenyl group. Further,examples of the arylene group include a phenylene group, a naphthylenegroup, a biphenylene group, an anthranylene group, a perilenylene group,a pyrenylene group, etc. Furthermore, examples of the substituentinclude an alkyl group having 1 to 10 carbon atoms, an alkoxy group or acyano group each having 1 to 10 carbon atoms respectively, etc. Withregard to the electron transfer compound, those compounds having a thinfilm forming capability are preferable.

Specific examples of the electron transfer compounds are shown below:

In addition, a material to be used for an electron injecting layer andan electron transferring layer includes any of compounds represented bythe following general formulae (A) to (G).

A nitrogen-containing heterocyclic derivative represented by a followinggeneral formula (A) or a following general formula (B):

In the general formulae (A) and (B), A¹ to A³ each independentlyrepresents nitrogen atom or carbon atom.

Ar¹ represents a substituted or unsubstituted aryl group having 6 to 60ring carbon atoms, or a substituted or unsubstituted hetero aryl grouphaving 3 to 60 ring carbon atoms, Ar₂ represents a hydrogen atom, asubstituted or unsubstituted aryl group having 6 to 60 ring carbonatoms, or a substituted or unsubstituted hetero aryl group having 3 to60 ring carbon atoms, a substituted or unsubstituted alkyl group having1 to 20 carbon atoms, or a substituted or unsubstituted alkoxy grouphaving 1 to 20 carbon atoms, or a bivalent group of these; Either Ar¹ orAr² is, however, a substituted or unsubstituted condensed ring grouphaving 10 to 60 ring carbon atoms or a substituted or unsubstitutedmonohetero condensed ring group having 3 to 60 ring carbon atoms.

L¹, L² and L each independently represents a single bond, a substitutedor unsubstituted arylene group having 6 to 60 ring carbon atoms, asubstituted or unsubstituted hetero arylene group having 3 to 60 ringcarbon atoms, or a substituted or unsubstituted fluorene group.

R represents hydrogen, a substituted or unsubstituted aryl group having6 to 60 ring carbon atoms, or a substituted or unsubstituted hetero arylgroup having 3 to 60 ring carbon atoms, a substituted or unsubstitutedalkyl group having 1 to 20 carbon atoms, or a substituted orunsubstituted alkoxy group having 1 to 20 carbon atoms. n represents aninteger of from 0 to 5, a plural number of R, if any, may be either thesame with or different from each other when n is 2. Further, a pluralnumber of R, if any, when these are adjacent to each other, may bebonded each other to form a carbocyclic aliphatic ring or a carbocyclicaromatic ring.

A nitrogen-containing heterocyclic derivative represented by a followinggeneral formula (C):HAr-L-Ar¹—Ar²  (C),

In the general formula (C), HAr represents a nitrogen-containingheterocyclic derivative and further may have a substituent, having 3 to40 of carbon atoms, L represents a single bond, an arylene group andfurther may have a substituent, having 6 to 60 carbon atoms, a heteroarylene group and further may have a substituent, having 3 to 60 carbonatoms, or a fluorene group and further may have substituent, Ar¹represents a bivalent aromatic hydrocarbon group and further may have asubstituent, having 6 to 60 carbon atoms, Ar² represents an aryl groupand further may have a substituent, having 6 to 60 carbon atoms or ahetero aryl group and further may have a substituent, having 3 to 60carbon atoms, represents a nitrogen-containing heterocyclic derivative.

A silacyclopentadiene derivative represented by a following generalformula (D):

In the general formula (D), X and Y each independently represents asubstituted or unsubstituted hydrocarbon group having 1 to 6 of carbonatoms, an alkoxy group, an alkenyloxy group, an alkynyloxy group, ahydroxyl group, a substituted or unsubstituted aryl group, a substitutedor unsubstituted hetero ring, or a structure forming a saturated orunsaturated ring by bonding X and Y, of R₁ to R₄ each representsindependently a hydrogen atom, a halogen atom, a substituted orunsubstituted alkyl group having 1 to 6 carbon atoms, an alkoxy group,an aryloxy group, a perfuluoroalkyl group, a perfuluoroalkoxy group, anamino group, an alkylcarbonyl group, an arylcarbonyl group, analkoxycarbonyl group, an aryloxycarbonyl group, an azo group, analkylcarbonyloxy group, an arylcarbonyloxy group, an alkoxycarbonyloxygroup, an aryloxycarbonyl group, a sulfunyl group, a sulfonyl group, asilyl group, a carbamoyl group, an aryl group, a heterocyclic group, analkenyl group, a nitro group, a formyl group, a nitroso group, aformyloxy group, an isocyano group, a cyanate group, a thiosyanategroup, an isothiosyanate group or a cyano group, or a substituted orunsubstituted condensed ling structure when these are adjacent to eachother.

A borane derivative represented by a following general formula (E):

In the general formula (E), R₁ to R₈ and Z₂ each independentlyrepresents a hydrogen atom, a saturated or unsaturated hydrocarbon, anaromatic group, an heterocyclic group, a substituted amino group, asubstituted boryl group, an alkoxy group or an aryloxy group, each of X,Y and Z₁ represents independently a saturated or unsaturatedhydrocarbon, an aromatic group, an heterocyclic group, a substitutedamino group, an alkoxy group or an aryloxy group, and substitutes of Z₁and Z₂ may bond each other to form a condesed ring, n represents aninteger of 1 to 3, Z₁ may be different from each other when n is 2 ormore; any compound, however, of which n is 1, X, Y and R₂ are methylgroups, and R₈ is a hydrogen atom or a substituted boryl group, or, ofwhich n is 3 and Z₁ is a methyl group, is excluded.

In the general formula (F), Q₁ and Q₂ each independently represents aligand shown by the general formula (G), L represents a ligand shown bya halogen atom, a substituted or unsubstituted alkyl group, asubstituted or unsubstituted cycloalkyl group, a substituted orunsubstituted aryl group, heterocyclic group, —OR¹ (R¹ represents ahydrogen atom, a substituted or unsubstituted alkyl group, a substitutedor unsubstituted cycloalkyl group, a substituted or unsubstituted arylgroup, or a substituted or unsubstituted heterocyclic group or —O—Ga-Q³(Q⁴) (Q³ and Q⁴ are the same with Q₁ and Q₂).

In the general formula (G), rings A¹ and A² have a six-member aryl-ringstructure and further may have a substituent, formed by condensing eachother.

The metal complex shows a strong property as a n-type impuritysemiconductor so that a capability of electron injection is significant.In addition, affinity between the metal complex formed and the ligand isstrong so that fluorescent quantum efficiency for a light emittingmaterial is increased.

The specific examples of a substituent for A¹ and A² forming a ligand ofthe general formula (G) include a halogen atom of halogen, bromine andiodine, a substituted or unsubstituted alkyl group such as a methylgroup, a ethyl group, a propyl group, a butyl group, a sec-butyl group,a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, anoctyl group, a stearyl group and trichloromethyl group, a substituted orunsubstituted aryl group such as a phenyl group, a naphtyl group, a3-methynaphtyl group, a 3-methoxynaphtyl group, a 3-fluorophenyl group,a 3-trichloromethylphenyl group, a 3-trifluoromethylphenyl group, and a3-nitrophenyl group, a substituted or unsubstituted alkoxy group such asa methoxy group, a n-butoxy group, a tert-butoxy group, atrichloromethoxy group, a trifluoroethoxy group, a pentafluoroporopoxygroup, a 2,2,3,3-tetra fluoroporopoxy group, a1,1,1,3,3,3-hexafluoro-2-propoxy group, a 6-(perfluoroethyl)hexyloxygroup, a substituted or unsubstituted aryloxy group such as a phenoxygroup, a p-nitrophenoxy group, a p-tert-butylphenoxy group, a3-fluorophenoxy group, a pentafluorophenoxy group, and a3-trifluoromethylphenoxy group, a substituted or unsubstituted alkylthiogroup such as a methylthio group, an ethylthio group, a tert-butykthiogroup, a hexylthio group, an octylthio group and a trifluromethylthiogroup, a substituted or unsubstituted arylthio group such as aphenylthio group, a p-nitrophenylthio group, a p-tert-butylphenylthiogroup, a 3-fluorophenylthio group, pentafiluorophenylthio group and3-trifluoromethylphenylthio group, a cyano group, a nitro group, anamino group, a mono or di substituted amino group such as a methyaminogroup, a dimethylamino group, a ethylamino group, a diethylamino group,a dipropylamino group, a dibutylamino group and a diphenylamino group,an acylamino group such as a bis(acetoxymethyl)amino group, abis(acetoxyethyl) amino group, a bis(acetoxypropyl)amino group andbis(acetoxybutyl)amino group, a hydroxy group, a siloxy group, an acylgroup, a carbamoyl group such as a methylcarbamoyl group,dimethylcarbamoyl group, an ethylcarbamoyl group, a diethylcarbamoylgroup, a propylcarbamoyl group, a butylcarbamoyl group andphenylcarbamoyl group, a carboxylic acid group, a sulfonic acid group,an imido group, a cycloalkyl group such as a cyclopentane group and acyclohexyl group, an aryl group such as a phenyl group, a naphthylgroup, a biphenyl group, an anthranyl group, a phenanthryl group, afluorenyl group and a pyrenyl group, and a heterocyclic group such as apyridinyl group, a pyrazinyl group, a pyrimidyl group, a pyridazinylgroup, a triazinyl group, an indolinyl group, a quinolinyl group, anacridinyl group, a pyrrolidyl group, a dioxanyl group, a morpholizinylgroup, a piperazinyl group, a triatinyl group, a carbazolyl group, afuranyl group, a thiophenyl group, an oxazolyl group, an oxadiazolylgroup, a benzoxazolyl group, a thiazolyl group, a thiadiazolyl group, abenzothiazolyl group, a triazolyl group, an imidazolyl group, abenzoimidazolyl group and a pranyl group. In addition, the abovesubstituent may bond each other to further form a six-member aryl ringor a hetero-ring.

In the present invention, it is preferable that a reductive dopant isadded in either the electron transporting zone or an interfacial zonebetween the cathode and the organic layer. The reductive dopant used inthe present invention is defined as a substance which reduces theelectron transporting compound. Examples of the reductive dopant includeat least one compound selected from alkali metals, alkali metalliccomplexes, alkali metal compounds, alkaline earth metals, alkaline earthmetallic complexes, alkaline earth metal compounds, rare earth metals,rare earth metallic complexes and rare earth metal compounds.

Examples of the preferable reductive dopant include at least one alkalimetal selected from a group consisting of Li (the work function: 2.93ev), Na (the work function: 2.36 eV), K (the work function: 2.28 eV), Rb(the work function: 2.16 eV) and Cs (the work function: 1.95 eV) or atleast one alkaline earth metals selected from a group consisting of Ca(the work function: 2.9 eV), Sr (the work function: 2.0 to 2.5 eV) andBa (the work function: 2.52 eV); whose work function of 2.9 eV orsmaller is particularly preferable. Among the above, the preferablereductive dopant include at least one alkali metal selected from a groupconsisting of K, Rb and Cs, the more preferred is Rb or Cs, and the mostpreferred is Cs. These alkali metals have particularly high ability ofreduction so that improvement of an emission luminance and longerlasting of a lifetime of the organic EL device may be realized. Inaddition, a combination of two or more of alkali metals is alsopreferable as a reductive dopant having 2.9 eV or less of the workfunction. In particular, a combination of Cs, for example with Na, Cs, Kor Rb, or Na and K is preferable. By combing and containing Cs therein,the reduction ability can be demonstrated effectively, and improvementof an emission luminance and longer lasting of a lifetime of the organicEL device may be realized by adding it into an electron injecting zone.

In the organic EL device of the present invention, an electron injectinglayer formed with an insulating material or a semiconductor may befurther sandwiched between the cathode and the organic thin film layer.The electron injecting layer effectively prevents leak in the electriccurrent and improves the electron injecting capability. It is preferablethat at least one metal compound selected from the group consisting ofalkali metal chalcogenides, alkaline earth metal chalcogenides, alkalimetal halides and alkaline earth metal halides is used as the insulatingmaterial. It is preferable that the electron injecting layer isconstituted with the above alkali metal chalcogenide since the electroninjecting property can be improved. Preferable examples of the alkalimetal chalcogenide include Li₂O, LiO, Na₂S, Na₂Se and NaO. Preferableexamples of the alkaline earth metal chalcogenide include CaO, BaO, SrO,BeO, BaS and CaSe. Preferable examples of the alkali metal halideinclude LiF, NaF, EF, LiCl, KCl and NaCl. Preferable examples of thealkaline earth metal halide include fluorides such as CaF₂, BaF₂, SrF₂,MgF₂ and BeF₂ and halides other than the fluorides.

Examples of the semiconductor constituting the electron transportinglayer include oxides, nitrides and nitriding oxides containing at leastone element selected from Ba, Ca, Sr, Yb, Al, Ga, In, Li, Na, Cd, Mg, SiTa, Sb and Zn, which are used singly or in combination of two or more.It is preferable that the inorganic compound constituting the electrontransporting layer is in the form of a fine crystalline or amorphousinsulating thin film. When the electron transporting layer isconstituted with the above insulating thin film, a more uniform thinfilm can be formed and defective pixels such as dark spots can bedecreased. Examples of the inorganic compound include the alkali metalchalcogenides, the alkaline earth metal chalcogenides, the alkali metalhalides and the alkaline earth metal halides which are described above.

As the cathode for the organic EL device of the present invention, anelectrode substance such as metal alloy, electroconductive compound andthose mixture having a small work function (4 eV or smaller) isemployed. Examples of the electrode substance include potassium,sodium-potassium alloy, magnesium, lithium, magnesium-silver alloy,aluminum/aluminum oxide, aluminum-lithium alloy, indium, rare earthmetal, etc.

The cathode can be prepared by forming a thin film of the electrodematerial described above in accordance with a process such as the vapordeposition process and the sputtering process.

When the light emitted from the light emitting layer is observed throughthe cathode, it is preferable that the cathode has a transmittance ofthe emitted light greater than 10%. It is also preferable that the sheetresistivity of the cathode is several hundred Ω/□ or smaller. Thethickness of the cathode is, in general, selected in the range of from10 nm to 1 μm and preferably in the range of from 50 to 200 nm.

In general an organic EL device tends to form defects in pixels due toleak and short circuit since an electric field is applied to ultra-thinfilms. To prevent the formation of the defects, a layer of an insulatingthin film may be inserted between the pair of electrodes.

Examples of the material employed for the insulating layer includealuminum oxide, lithium fluoride, lithium oxide, cesium fluoride, cesiumoxide, magnesium oxide, magnesium fluoride, calcium oxide, calciumfluoride, aluminum nitride, titanium oxide, silicon oxide, germaniumoxide, silicon nitride, boron nitride, molybdenum oxide, ruthenium oxideand vanadium oxide. Mixtures and laminates of the above compounds canalso be employed.

To produce an organic EL device of the present invention, for example, acathode, a light emitting layer and, where necessary, a hole injectinglayer and an electron injecting layer are formed in accordance with theaforementioned process using the aforementioned materials, and the anodeis formed in the last step. An organic EL device may be produced byforming the aforementioned layers in the order reverse to that describedabove, i.e., an anode being formed in the first step and a cathode inthe last step.

An embodiment of the process for producing an organic EL device having aconstruction in which a cathode, a hole injecting layer, a lightemitting layer, an electron injecting layer and an anode are disposedsequentially on a light-transmitting substrate will be described in thefollowing.

On a suitable light-transmitting substrate, a thin film made of amaterial for the cathode is formed in accordance with the vapordeposition process or the sputtering process so that the thickness ofthe formed thin film is 1 μm or smaller and preferably in the range of10 to 200 nm. The formed thin film is employed as the cathode. Then, ahole injecting layer is formed on the cathode. The hole injecting layercan be formed in accordance with the vacuum vapor deposition process,the spin coating process, the casting process or the LB process, asdescribed above. The vacuum vapor deposition process is preferable sincea uniform film can be easily obtained and the possibility of formationof pin holes is small.

When the hole injecting layer is formed in accordance with the vacuumvapor deposition process, in general it is preferable that theconditions in general are suitably selected in the following ranges:temperature of the deposition source: 50 to 450° C.; vacuum level: 10⁻⁷to 10⁻⁸ Torr; deposition rate: 0.01 to 50 nm/second; temperature of thesubstrate: −50 to 300° C.; and film thickness: 5 nm to 5 μm; althoughthe conditions of the vacuum vapor deposition are different depending onthe employed compound (the material for the hole injecting layer) andthe crystal structure and the recombination structure of the holeinjecting layer to be formed.

Subsequently, the light-emitting layer is formed on the hole-injectinglayer formed above. Also the formation of the light emitting layer canbe made by forming the light emitting material according to the presentinvention into a thin film in accordance with the vacuum vapordeposition process, the sputtering process, the spin coating process orthe casting process. The vacuum vapor deposition process is preferablebecause a uniform film can be easily obtained and the possibility offormation of pinholes is small. When the light-emitting layer is formedin accordance with the vacuum vapor deposition process, in general, theconditions of the vacuum vapor deposition process can be selected in thesame ranges as those described for the vacuum vapor deposition of thehole-injecting layer although the conditions are different depending onthe used compound. It is preferable that the thickness is in the rangeof from 10 to 40 nm.

Next, the electron-injecting layer is formed on the light-emitting layerformed above. Similarly to the hole injecting layer and thelight-emitting layer, it is preferable that the electron-injecting layeris formed in accordance with the vacuum vapor deposition process since auniform film must be obtained. The conditions of the vacuum vapordeposition can be selected in the same ranges as those for the holeinjecting layer and the light-emitting layer.

In the last step, the anode is formed on the electron injecting layer,and an organic EL device can be fabricated. The anode is made of a metaland can be formed in accordance with the vacuum vapor deposition processor the sputtering process.

It is preferable that the vacuum vapor deposition process is employed inorder to prevent the lower organic layers from damages during theformation of the film. In the above production of the organic EL device,it is preferable that the above layers from the anode to the cathode areformed successively while the production system is kept in a vacuumafter being evacuated.

The process for forming the layers in the organic EL device of thepresent invention is not particularly limited. A conventional processsuch as the vacuum vapor deposition process and the spin coating processcan be used. The organic thin film layer comprising the compound havinga spiro bond represented by the foregoing general formula (1) used inthe organic EL device of the present invention can be formed inaccordance with the vacuum vapor deposition process, the molecular beamepitaxy process (the MBE process) or, using a solution prepared bydissolving the compound into a solvent, in accordance with aconventional coating process such as the dipping process, the spincoating process, the casting process, the bar coating process and theroller coating process.

The thickness of each layer in the organic thin film layer in theorganic EL device of the present invention is not particularly limited,therefore, a thickness within the range of several nanometers to 1 μm ispreferable so as to reduce the defects such as pin holes and improve theefficiency.

When a direct voltage is applied on the organic EL device produced inthe above manner, when a direct voltage of 5 to 40 V is applied in thecondition that the cathode is connected to a positive electrode (+) andthe anode is connected to a negative electrode (−), then a lightemitting is observed. When the connection is reversed, no electriccurrent is produced and no light is emitted at all. When an alternatingvoltage is applied on the organic EL device, the uniform light emissionis observed only in the condition that the polarity of the cathode ispositive and the polarity of the anode is negative. When an alternatingvoltage is applied on the organic EL device, any type of wave shape canbe employed.

EXAMPLE

This invention will be described in further detail with reference toExamples, which does not limit the scope of this invention.

Synthesis Example 1 Synthesis of Compound (AN-2) (1) Synthesis ofIntermediate [1-bromo-6-(4-naphthalene-1-yl-phenyl)pyrene]

7.4 g of 4-(naphthalene-1-yl)phenyl boronic acid prepared by a wellknown method and 7.0 g of conventional 1-bromopyrene were dissolved in80 ml of dimethoxyethane (DME). Subsequently, 0.58 g oftetrakistriphenylphosphine palladium and 40 ml of 2M-sodium carbonateaqueous solution were added therein, followed by argon displacement.After heating and refluxing over 8 hours, it was stood to cool and thenan organic layer was extracted therefrom by toluene. The organic layerwas washed by saturated salt water, followed by drying through anhydroussodium sulfate, and then the organic solvent was removed by anevaporator. The residue was refined through a silica gel chromatography(a developing solvent: toluene) and then 10.0 g of1-(4-naphthalene-1-yl-phenyl) pyrene was obtained. (yield: 99%)

10.0 g of 1-(4-naphthalene-1-yl-phenyl)pyrene obtained was dispersedinto 100 ml of dimethyl formaldehyde (DMF), and 5.3 g N-bromosuccinamide(NBS) in DMF solution was dropped therein at room temperature. Afterstirred over 6 hours, it was left around overnight. After the overnight,150 ml of water was added to it and the deposited crystal was filtrated,followed by water and ethanol washing of the crystal. The crystalobtained was refined through a silica gel chromatography (a developingsolvent: hexane/toluene=2/1) and then 4.5 g of1-bromo-6-(4-naphthalene-1-yl-phenyl)pyrene (the yield: 38%) and 3.8 gof 1-bromo-8-(4-naphthalene-1-yl-phenyl)pyrene were obtained (the yield:32%) as the intermediates.

(2) Synthesis of Compound (AN-2)

2.7 g of (4-naphthalene-2-yl)phenyl boronic acid prepared by a wellknown method and 4.5 g of 1-bromo-6-(4-naphthalene-1-yl-phenyl)pyrenewere dissolved in 40 ml of DME. Subsequently, 0.22 g oftetrakistriphenylphosphine palladium and 15 ml of 2M-sodium carbonateaqueous solution were added therein, followed by argon displacement.After heating and refluxing over 9 hours, it was stood to cool and anorganic layer was extracted therefrom by toluene. The organic layer waswashed by saturated salt water, followed by drying through anhydroussodium sulfate, and then the organic solvent was removed by anevaporator. The residue was refined through a silica gel chromatography(a developing solvent: hexane/toluene=1/1) and then 3.1 g of theobjective compound (AN-2) was obtained.

The measurement result of the compound by FD-MS (Field Desorption MassSpectrometry analysis) showed m/z=606 to C₄₈H₃₀=606, therefore theobjective compound (AN-2) was confirmed (the yield: 54%).

Synthesis Example 2 Synthesis of Compound (AN-7)

2.3 g of 3-(naphthalene-2-yl)phenyl boronic acid prepared by a wellknown method and 3.8 g of 1-bromo-8-(4-naphthalene-1-yl-phenyl) pyrenewere dissolved in 40 ml of DME. Subsequently, 0.19 g oftetrakis(triphenylphosphine)palladium and 13 ml of 2M-sodium carbonateaqueous solution were added therein, followed by argon displacement.After heating and refluxing for 9 hours, it was stood to cool and thenan organic layer was extracted therefrom by toluene. The organic layerwas washed by saturated salt water, followed by drying through anhydroussodium sulfate, and then the organic solvent was removed by anevaporator. The residue was refined through a silica gel chromatography(a developing solvent: hexane/toluene=1/1) and then 2.7 g of theobjective compound (AN-7) was obtained.

The measurement result of the compound by FD-MS showed m/z=606 toC₄₈H₃₀=606, therefore the objective compound (AN-7) was confirmed (theyield: 58%).

Synthesis Example 3 Synthesis of Compound (AN-3) (1) Synthesis ofIntermediate [1-bromo-6-(naphthalene-1-yl)pyrene]

1-naphthalene boronic acid in place of 4-(naphthalene-1-yl)phenylboronic acid was used in Synthesis Example 1 (1), and then1-bromo-6-(naphthalene-1-yl) pyrene and 1-bromo-8-(naphthalene-1-yl)pyrene were obtained.

(2) Synthesis of Compound (AN-3)

The procedure of Synthesis Example 1 (2) was repeated except that 4.0 gof 1-bromo-6-(naphthalene-1-yl)pyrene and 1.85 g of 2-naphthaleneboronic acid in place of 4-(naphthalene-2-yl)phenyl boronic acid and1-bromo-6-(4-naphthalene-1-yl-phenyl)pyrene were used, and then 2.7 g ofthe light-yellow crystalline objective compound (AN-3) was obtained.

The measurement result of the compound by FD-MS showed m/z=454 toC₃₆H₂₂=454, therefore the objective compound (AN-3) was confirmed.

Synthesis Example 4 Synthesis of Compound (AN-19)

The procedure of the synthesis example 1 (2) was repeated except that4.0 g of 1-bromo-8-(naphthalene-1-yl)pyrene obtained in SynthesisExample 3 (1) and 1.86 g of 2-naphthalene boronic acid in place of4-(naphthalene-2-yl)phenyl boronic acid and1-bromo-6-(4-naphthalene-1-yl-phenyl)pyrene were used, and then 2.9 g ofthe light-yellow crystalline objective compound (AN-19) was obtained.

The measurement result of the compound by FD-MS showed m/z=454 toC₃₆H₂₂=454, therefore the objective compound (AN-19) was confirmed.

Synthesis Example 5 Synthesis of Compound (AN-20)

5.0 g of the compound (AN-3) was dispersed in 50 ml of DMF and 4.0 g ofNBS in DMF solution was dropped thereto at room temperature. After 3days reaction, 100 ml of water was added thereto, and the depositedcrystal was filtrated, followed by water and ethanol-washing of thecrystal. The crystal obtained was refined through a silica gelchromatography (a developing solvent: hexane/toluene=2/1) and then 4.0 gof 1,6-dibromo-3-(naphthalene-2-yl)-8-(naphthalene-1-yl) pyrene wasobtained as the intermediate (the yield: 60%).

4.0 g of 1,6-dibromo-3-(naphthalene-2-yl)-8-(naphthalene-1-yl)pyreneobtained and 1.9 g of phenyl boronic acid were dissolved in 60 ml ofDME. Subsequently, 0.5 g of tetrakistriphenylphosphinepalladium and 20ml of 2M-sodium carbonate aqueous solution were added therein, followedby argon displacement. After heating and refluxing over 8 hours, it wasstood to cool and then the deposited crystal was filtrated. Afterwashing the crystal by water and methanol it was refined through asilica gel chromatography (a developing solvent: toluene), and then 2.9g of the light-yellow crystalline objective compound (AN-20) wasobtained.

The measurement result of the compound by FD-MS showed m/z=606 toC₄₈H₃₀=606, therefore the objective compound (AN-20) was confirmed (theyield: 73%).

Synthesis Example 6 Synthesis of Compound (AN-21) (1) Synthesis ofIntermediate [1-bromo-3,8-dinaphthalene-2-yl-6-phenylpyrene]

8.0 g of 1,6-dinaphthalene-2-yl-pyrene prepared by a well known methodwas dispersed into 80 ml of DMF, and 3.2 g of NBS in DMF solution wasdropped therein at room temperature. After 3 days reaction, 150 ml ofwater was added to it and the deposited crystal was filtrated, followedby water and ethanol washing of the crystal. The crystal obtained wasrefined through a silica gel chromatography (a developing solvent:hexane/toluene=2/1) and then 8.5 g of3-bromo-1,6-dinaphthalene-2-yl-pyrene was obtained as the intermediate(the yield: 90%). 8.5 g of 3-bromo-1,6-dinaphthalene-2-yl-pyreneobtained and 2.3 g of phenyl boronic acid were dissolved in 100 ml ofDME. Subsequently, 0.65 g of tetrakistriphenylphosphinepalladium and 25ml of 2M-sodium carbonate aqueous solution were added therein, followedby argon displacement. After heating and refluxing over 8 hours, it wasstood to cool and then the deposited crystal was filtrated. Afterwashing the crystal by water and methanol it was refined through asilica gel chromatography (a developing solvent: toluene), and then 5.4g of 1,6-dinaphthalene-2-yl-3-phenylpyrene of the light-yellowcrystalline was obtained (the yield: 64%).

5.4 g of 1,6-dinaphthalene-2-yl-3-phenylpyrene was dispersed into 60 mlof DMF, and 1.9 g NBS in DMF solution was dropped therein at roomtemperature. After 3 days reaction, 150 ml of water was added to it andthe deposited crystal was filtrated, followed by water and ethanolwashing of the crystal.

The crystal obtained was refined through a silica gel chromatography (adeveloping solvent: hexane/toluene=2/1) and then 5.9 g of1-bromo-3,8-dinaphthalene-2-yl-6-phenylpyrene was obtained as theintermediate (the yield: 95%).

(2) Synthesis of Compound (AN-21)

5.9 g of 1-bromo-3,8-dinaphthalene-2-yl-6-phenylpyrene obtained and 2.3g of 2-biphenyl boronic acid were dissolved in 80 ml of DME.Subsequently, 0.35 g of tetrakistriphenylphosphinepalladium and 15 ml of2M-sodium carbonate aqueous solution were added therein, followed byargon displacement. After heating and refluxing over 7 hours, it wasstood to cool and then the deposited crystal was filtrated. Afterwashing the crystal by water and methanol, it was refined through asilica gel chromatography (a developing solvent: toluene), and then 4.8g of the light-yellow crystalline objective compound (AN-21) wasobtained.

The measurement result of the compound by FD-MS showed m/z=682 toC₅₄H₃₄=682, therefore the objective compound (AN-21) was confirmed (theyield: 73%).

Synthesis Example 7 Synthesis of Compound (AN-8)

10 g of 2,7-diiodo-9,9′-dimetyl-9H-fluorene prepared by a well knownmethod and 4.6 g of 1-naphthalene boronic acid were dissolved in 150 mlof toluene. Subsequently, 0.78 g of tetrakistriphenylphosphinepalladiumand 35 ml of 2M-sodium carbonate aqueous solution were added therein,followed by argon displacement. After heating and refluxing over 8hours, it was stood to cool and then an organic layer was extractedtherefrom by toluene. The organic layer was washed by saturated saltwater, followed by drying through anhydrous sodium sulfate, and then theorganic solvent was removed by an evaporator. The residue was refinedthrough a silica gel chromatography (a developing solvent:hexane/toluene=1/1) and then 7.1 g ofdiiodo-9,9′-dimetyl-7-naphthalene-1-yl-9H-fluorene was obtained (theyield: 71%).

7.1 g of diiodo-9,9′-dimetyl-7-naphthalene-1-yl-9H-fluorene obtained and4.7 g of 1-pyrene boronic acid were dissolved in 100 ml of DME.Subsequently, 0.55 g of tetrakistriphenylphosphinepalladium and 25 ml of2M-sodium carbonate aqueous solution were added therein, followed byargon displacement. After heating and refluxing over 7 hours, it wasstood to cool and then the deposited crystal was filtrated. Afterwashing the crystal by water and methanol it was refined through asilica gel chromatography (a developing solvent: toluene), and then 5.7g of the light-yellow crystalline objective compound (AN-8) wasobtained.

The measurement result of the compound by FD-MS showed m/z=520 toC₄₁H₂₈=520, therefore the objective compound (AN-8) was confirmed (theyield: 69%).

Example 1 Fabrication of an Organic EL Device

A glass substrate (manufactured by GEOMATEC Company) of 25 mm×75 mm×1.1mm thickness having an ITO transparent electrode was cleaned byapplication of ultrasonic wave in isopropyl alcohol for 5 minutes andthen by exposure to ozone generated by ultraviolet light for 30 minutes.The cleaned glass substrate having an ITO transparent electrode line wasfixed to a substrate holder of a vacuum deposition apparatus, and on thesurface, where the ITO transparent electrode line was fixed, of thesubstrate, a film (hereinafter referred to as TPD232 film) having filmthickness of 60 nm of the followingN,N′-bis(N,N′-diphenyl-4-aminophenyl)-N,N-diphenyl-4,4′-diamino-1,1′-biphelwas formed so as to cover the transparent electrode. The TPD232 filmperforms as a hole injecting layer. Subsequently, a layer having layerthickness of 20 nm of the followingN,N,N′,N′-tetra(4-biphenyl)-diaminobiphenylene was formed (hereinafterreferred to as TBDB layer). The layer performs as a hole transportinglayer. Subsequently, a film having a film thickness of 40 nm of theaforementioned compound AN-2 was formed as host material by a vapordeposition. Concurrently, as light emitting material, the followingamino compound BD1 containing a styryl group was deposited at the ratioby weight between AN-2 and BD 1 of 40:3 by a vapor deposition. The filmperforms as a light emitting layer. On the film, a film having a Alqfilm thickness of 10 nm was formed. The film performs as an electroninjecting layer. Further, a film (film thickness: 10 nm) of Alq:Li (thesource of lithium: manufactured by SAES GETTERS Company) as an electroninjecting layer was formed by binary vapor deposition of Li as areductive dopant and the following Alq. On the Alq:Li film, Al metal wasdeposited to form a metal cathode, therefore, an organic EL device wasfabricated.

The device was tested by passing electric current, an emission luminanceof 615 cd/m² and a current efficiency of 6.5 cd/A was observed at avoltage of 5.76V and a current density of 10 mA/cm². In addition, whenthe EL device was continuously tested by passing electric current at aninitial luminance of 1,000 cd/m², the results of the half-lifetime areshown in Table 1.

Examples 2 to 4 Fabrication of Organic EL Devices

Organic EL devices were fabricated similar to Example 1 except that thecompounds described in Table 1 were used in place of the compound(AN-2).

The devices obtained were tested by passing electric current similar tothe example 1, the results of the half-lifetime measured at an initialluminance of 1,000 cd/m², are shown in Table 1.

Comparative Example 1 to 3

Organic EL devices were fabricated similar to the example 1 except thatthe following compounds an-1 (Comparative Example 1), an-2 (ComparativeExample 2) and an-3 (Comparative Example 3) were used in place of thecompound (AN-2).

The devices obtained were tested by passing electric current similar tothe example 1, the results of the half-lifetime measured at an initialluminance of 1,000 cd/m², were described in Table 1.

TABLE 1 Material Forming a Light Driving Current Emitting VoltageLuminance Efficiency Chromaticity Half-Lifetime Layer (V) (cd/m²) (cd/A)Coordinate (x,y) (hours) Example 1 AN-2/BD1 5.76 615 6.15 (0.151,0.174)2800 Example 2 AN-3/BD1 5.79 611 6.11 (0.151,0.177) 2000 Example 3AN-9/BD1 5.64 645 6.45 (0.148,0.198) 1700 Example 4 AN-8/BD1 5.86 6166.16 (0.147,0.183) 1500 Comparative an-1/BD1 6.85 531 5.31 (0.170,0236)490 Example 1 Comparative an-2/BD1 6.89 550 5.50 (0.199,0.230) 800Example 2 Comparative an-3/BD1 6.89 558 5.58 (0.159,0229) 700 Example 3

INDUSTRIAL APPLICABILITY

As aforementioned in detail, an organic EL device employing a compoundhaving an asymmetric pyrene derivative of the present invention exhibitsa great efficiency of light emission and has a long lifetime.

Therefore, they are highly applicable as the organic EL devices supposedto be used continuously for long years.

1. An asymmetric pyrene derivative represented by a following generalformula (1):

wherein, Ar and Ar′ each represents a substituted or unsubstitutedaromatic group having 6 to 50 ring carbon atoms; L and L′ eachrepresents a substituted or unsubstituted phenylene group, a substitutedor unsubstituted naphthalenylene group, a substituted or unsubstitutedfluorenylene group or a substituted or unsubstituted dibenzosilolylenegroup; m represents an integer of 0 to 2, n represents an integer of 1to 4, s represents an integer of 0 to 2 and t represents an integer of 0to 4; and L or Ar bonds to any one of 1 to 5 positions of the pyrene,and also L′ or Ar′ bonds to any one of 6 to 10 thereof; however, whenn+t is an even number, Ar, Ar′, L and L′ satisfy a following requirement(1) or requirement (2): (1) Ar≠Ar′ and/or L≠L′ (wherein ≠ means thateach group has a different structure), (2) when Ar=Ar′ and L=L′, (2-1)m≠B and/or n≠t, or (2-2) when m=s and n=t; (2-2-1) both L and L′ orpyrene bond respectively to a different position of Ar and Ar′ or(2-2-2) both L and L′ or pyrene bond respectively to the same positionof Ar and Ar′ excluding a case where both L and L′ or both Ar and Ar′bond respectively to 1 and 6, or 2 and 7 positions thereof.
 2. Theasymmetric pyrene derivative according to claim 1, wherein Ar≠Ar′ in thegeneral formula (1).
 3. The asymmetric pyrene derivative according toclaim 1, wherein L≠L′ in the general formula (1).
 4. The asymmetricpyrene derivative according to claim 1, wherein Ar=Ar′ and L≠L′, and m≠sand/or n≠t in the general formula (1).
 5. The asymmetric pyrenederivative according to claim 1, wherein m=s and n=t, and wherein thefollowing requirement (2-2-1) or (2-2-2) is satisfied in the generalformula (1); (2-2-1) both L and L′ or pyrene each bonds respectively todifferent positions of Ar and Ar′, (2-2-2) both L and L′ or pyrene eachbonds respectively to the same positions of Ar and Ar′, excluding a casewhere both L and L′ or both Ar and Ar′ bond to 1 and 6 positionsthereof, or 2 and 6 positions thereof.
 6. An asymmetric pyrenederivative represented by a following general formula (2):

wherein, Ar and Ar′ each represents a substituted or unsubstitutedaromatic group having 6 to 60 ring carbon atoms; L and L′ eachrepresents a substituted or unsubstituted pheylene group, a substitutedor unsubstituted naphthalenylene group, a substituted or unsubstitutedfluorenylene group or a substituted or unsubstituted dibenzosilolylenegroup; m represents an integer of 0 to 2, s represents an integer of 0to 2 and t represents an integer of 0 to 4; and L′ or Ar′ bonds to anyone of 2 to 10 positions of pyrene; however, when t is an odd number,Ar, Ar′, L and L′ satisfy the following requirement (1′) or arequirement (2′): (1′) Ar≠Ar′ and/or L≠L′ (wherein ≠ means that eachgroup has a different structure), (2′) when Ar=Ar′ and L=L′, (2-1′) m≠sand/or n≠t, or (2-2′) when m=s and n=t, (2-2-1′) both L and L′ or pyreneeach bonds respectively to different positions of Ar and Ar′, or(2-2-2′) both L and L′ or pyrene each bonds to the same positions of Arand Ar′, excluding a case where L′ or Ar′ bonds to 6 position thereof.7. The asymmetric pyrene derivative according to claim 6, wherein Ar≠Ar′in the general formula (2).
 8. The asymmetric pyrene derivativeaccording to claim 6, wherein L≠L′ in the general formula (2).
 9. Theasymmetric pyrene derivative according to claim 6, wherein Ar=Ar′ andL≠L′, and m≠s and/or n≠t in the general formula (2).
 10. The asymmetricpyrene derivative according to claim 6, wherein, m=s and n=t, andwherein the following requirement (2-2-1′) or (2-2-2′) is satisfied inthe general formula (1): (2-2-1′) both L and L′ or pyrene each bondsrespectively to different positions of Ar and Ar′, (2-2-2′) both L andL′ or pyrene each bonds respectively to the same positions of Ar andAr′, excluding a case where L′ or Ar′ bonds to 6 position thereof. 11.An asymmetric pyrene derivative represented by a following generalformula (3):

wherein, Ar and Ar′ each represents a substituted or unsubstitutedaromatic group having 6 to 50 ring carbon atoms; L and L′ eachrepresents a substituted or unsubstituted phenylene group, a substitutedor unsubstituted naphthalenylene groups a substituted or unsubstitutedfluorenylene group or a substituted or unsubstituted dibenzosilolylenegroup; m represents an integer of 0 to 2 and a represents an integer of0 to
 2. 12. The asymmetric pyrene derivative according to any one ofclaims 1 to 11, which is a light emitting material for an organicelectroluminescence device.
 13. The asymmetric pyrene derivativeaccording to any one of claims 1 to 11, which is a host material for anorganic electroluminescence device.
 14. An organic electroluminescencedevice which comprises at least one organic thin film layer including alight emitting layer sandwiched between a pair of electrode consistingof an anode and a cathode, wherein the organic thin film layer comprisesat least one kind selected from asymmetric pyrene derivatives accordingto any one of claims 1 to 10 singly or as its mixture component.
 15. Theorganic electroluminescence device according to claim 14, wherein thelight emitting layer comprises any one of the organic pyrene derivativesaccording to claims 1 to 11 as a host material.
 16. The organicelectroluminescence device according to claim 14, wherein the lightemitting layer further comprises an arylamine compound.
 17. The organicelectroluminescence device according to claim 14, wherein the lightemitting layer further comprises a styrylamine compound.